This invention relates to irrigation systems and in particular to a tire assembly for mobile irrigation structures that prevents ruts from forming in the soil.
Irrigation systems are commonly used in agricultural operations such as, for example, large scale commercial farms. One common type of such a system is a center-pivot irrigation system which typically employs an elongate boom that is connected at one end to a center pivot which acts as a water source for the boom. Typically, the boom is comprised of a plurality of pipes connected together extending away from the center pivot with sprinklers or other watering devices located along the length of the boom to spray water across the soil. The boom is elevated and supported by a number of mobile towers with wheels for transport across the ground. One of the towers acts as a drive tower so that the boom travels in wide circles about the center pivot. Some of the center pivot systems employ a corner sweep unit for systems that are located near the corner of a plot of land. The corner sweep unit is located at the end of the boom opposite the center pivot. The corner sweep unit pivots about it""s own axis as the corner sweep unit approaches the corner of the property as the boom rotates. Corner sweep units maximize the use of irrigation water in tight corners to ensure irrigation of the most amount of soil. Another common type of irrigation equipment is known as a linear system that typically uses the same type of equipment described above but that travel along a straight path instead of a circular path. These irrigation systems are typically repeatedly driven along their paths for a period of time to adequately irrigate the land.
These irrigation systems create very wet soil conditions over which the irrigation equipment must necessarily travel. Most current irrigation equipment systems employ tires that have a tread such as, for example, a tractor tread tire on the towers to move the system across the ground. One problem with such tires is that the tread in the tires directs water to the center of the path along which the tire travels causing further saturation of the soil creating a very muddy and soggy travel path. Because the irrigation systems are driven over the same path for long periods of time ruts eventually develop along the path. The weight of the irrigation equipment along with the soggy soil along the travel path contributes to the formation of ruts. Depending on the type of soil and how long the irrigation system travels over the same path the ruts can become several feet deep. Ruts as deep as five or six feet deep have been known to be formed.
These ruts cause several problems. One problem is that the tires of the tower may become stuck so that the tower is unable to continue along the path. With very deep ruts, parts of the tower itself may engage the ground and may become stuck. For example, the towers form a frame that supports the boom and the tires. The frame may include cross struts that extend between front and back members of the frame located several feet above the ground surface. Some ruts are so deep that the cross struts are at ground level and drag along the ground surface and may become stuck. Parts of the irrigation equipment may experience damage or failure. Furthermore, a tractor or other large vehicle must be utilized to pull the tower from its stuck position. This increases the time and expense of irrigation.
Another problem caused by ruts is that they can damage other agricultural vehicles that travel across the field. For example, some commercial farm vehicles such as fertilizers typically travel across a crop field at a speed of about 15 mph. Some of these vehicles use a boom of between 80-100 ft. long to disperse fertilizer across the crop field. Other vehicles or equipment such as hay balers and harvesters carry heavy loads. Traveling across ruts at such speeds puts great stress on the vehicles and they may experience damage. Significant damage may occur with very deep ruts. In order to avoid damage the vehicles must slow down each time a rut is encountered. Since the vehicles are unable to travel at a constant speed production time and labor costs are increased.
Yet another problem caused by ruts is erosion. Erosion is a problem encountered with many agricultural endeavors. Ruts magnify the erosion problem by providing a channel in which the irrigation water or rain water washes away topsoil. This is especially problematic on land that slopes or on farmed land located on hillsides. In some instances the washed-away soil may be recovered and hauled back to its original location. If the washed-away soil is not recoverable new soil must then be brought in and distributed over the eroded land. In addition to damage to the land such erosion causes increased expense for soil recovery and/or replacement.
Some attempts to solve the problem with ruts include filling the ruts with straw, wood chips, compost, gravel, concrete or debris. This attempt has not proved to be acceptable because of land pollution and contamination issues. Successive land owners may experience damage to some equipment and may be required at great expense to clean up and remove the fill material. If contamination of the soil is an issue additional costs must be incurred to remove such contaminants.
Other attempts to fill the ruts include the use of commercially available clotting pellets or other clumping material that hardens when wet. However, such products have proved to be inconsistently effective. Additionally, these products must be purchased every time a rut is formed which increases costs and requires continued maintenance.
One prior art device that attempts to prevent formation of ruts utilizes a ground engaging track for the tower wheels. The track comprises flat plates or sections that are hinged together around the tire. The device has side walls that extend down the sides of the tire. The problem with such a device is that the hinges wear out which may cause damage and require repair or replacement of the device. The side walls of the device also pinch the sides of the tires causing wear and damage to the tires. Additionally, if the device encounters a rocky patch in the soil the device may get stuck or stall causing the tire to spin inside the track. Furthermore, such a device experiences vibration which loosens lug nuts on wheels and causes noise.
Other attempts to prevent ruts from forming include the use of steel wheels. However, such wheels are very heavy and place a great deal of stress on the axle and/or gear box of the tower drive mechanism. Additionally, such steel wheels require a vehicle such as, for example, a front end loader to attach the steel wheel to the tower.
The present invention provides a device for irrigation systems that prevents the formation of ruts caused by repeated travel along a path by tires of a mobile vehicle or structure. The irrigation system includes an elongate boom connected at one end to a center pivot which acts as a water source for the boom. The boom includes a plurality of pipes connected together to extend away from the center pivot with sprinklers located along the length of the boom to spray water across the soil. The boom is elevated and supported by a number of mobile towers each of which has a tire assembly for transporting the tower and, thus, the boom across the ground in wide circles about the center pivot.
Each tire assembly includes dual tires mounted on an axle with a flexible belt member wrapped around the outer periphery of the two tires. The flexible belt member includes a plurality of cleat members located on the outer surface of the flexible belt member. The cleat members comprise channel elements that extend across the width of the flexible belt member. The channel elements have opposed side walls extending away from a base connected to the outer surface of the flexible belt member. At least one center guide and preferably a plurality of center guides are connected to the inner surface of the flexible belt member to keep the belt in place.
The flexible belt member is essentially a flat member having a length and a width and is adapted to be wrapped around the dual tires so that the center guides are located between the tires and the cleat members are located on the outer periphery of the tire assembly. The flexible belt member includes means to secure the ends of the flexible belt member when it is mounted on the tire assembly.
The tire assembly reduces soil compaction by providing a greater ground engaging surface area to more evenly distribute the weight of the equipment. Furthermore, the cleat members engage the ground to provide traction and to direct water away from the center of the travel path to the outer sides of the travel path. Therefore, the tire assembly of the present invention substantially prevents ruts from forming in loose soil and/or wet ground conditions.
Most center pivot irrigation systems are designed so that the tires on the mobile structure are canted or mounted on an angle from the vertical extending away from the center pivot. Another aspect of the invention is to inflate one tire to an inflation pressure that is approximately twice that of the other tire. Specifically, the inner tire or the tire located toward the center pivot is inflated to about twice the pressure of the outside tire. This prevents too much torque pressure from being applied to the tire assembly drive mechanism.
The invention is particularly effective in wet or loose soil environments created by irrigation systems and/or farming activities for large or commercial farms. Although the invention is described as being used primarily with center pivot irrigation systems. However, it is contemplated that the present invention not be limited to center pivot irrigation systems but may also be used with other irrigation systems such as, for example, linear irrigation systems and other mobile structures in which the formation of ruts in the ground is a problem.
It is therefore an object of the present invention to provide a tire assembly for mobile structures that substantially prevents ruts from forming in the ground.
Another object of the invention is to provide a tire assembly that provides a greater ground engaging surface area over which the weight of the equipment is distributed to reduce soil compaction.
Still another object of the invention is to provide a tire assembly that directs water away from the center of the travel path.
A further object of the invention is to provide a tire assembly that can be assembled with two people.
Yet another object of the invention is to reduce soil erosion, pollution, and contamination.
Still another object of the invention is to provide a tire assembly for use with a variety of irrigation systems.
Another object of the invention is to provide a rut prevention device that is economical in manufacture and durable in use
These and other objects will be apparent to those skilled in the art.